Well i start up LFS and go to single player and chose the track then i click ok and the gane crashes.

and it does the same when i try join a server

i'm using the demo version

Can you be more specific please?

Does it give any errors? What is your system spec? What Windows?

other than that, I can only say to reinstall LFS.

I think that you have probably modded up your lfs too much. Try reinstalling the game and tell us the results.

Modding is not the issue, well it never was on lfs for me.

Really, it has nothing to do with modding here

Once, my lfs had the same problem when i modded it. After reinstall i didnt put those mods in and it worked well.